A glen is a valley that is typically long and narrow, with gently sloped concave sides, unlike a ravine which is deep and bounded by steep slopes. It is a long, deep valley with steep or vertical sides, sometimes U-shaped as formed by a glacier, and may have a river or stream flowing in the middle. Glens are often found in mountainous areas and are appreciated by tourists for their tranquility and scenery. The word "glen" is Goidelic in origin, meaning "valley" in Irish and Scottish Gaelic, and "glen" also occurs often in place names. Some examples of glens include the Glens of Antrim in Northern Ireland, Glen Onoko in Pennsylvania, and Watkins Glen in New York. In summary, a glen is a narrow, secluded valley that is often found in mountainous areas and may have a river or stream flowing through it.